xws is a multi-user chat server that also hosts crossword puzzles. Or perhaps it's a multi-player crossword puzzle engine that also supports chatting amongst its players. Whichever it is, it understands the popular [Across Lite] puzzle file format.

xws is not a 'web chat server. It is a plain text server, similar to other chatters or MUDs. It prefers telnet or MUD clients (especially the line mode varieties).